Want to start making a Boid flocking system but having a hard time finding a way to check for other objects (in my case enemies of the same class of the one that is checking) in a certain radius around another object. I found the Physics.OverlapSphere method but that returns colliders, not gameobjects and their transforms. Is that what i want to use or is there another way?
Physics.OverlapSphere is the way to go. You can then access Collider.gameObject or Collider.transfrom.
The other methods are
- Check every single object for distance
- Implement your own spatial partitioning structure
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Thanks for clearing that up!
If you need to know how many GameObjects are around at any time, you should maybe use a trigger collider following the object that need to know how many GameObjects are around.
Add a new script to it and in a OnTriggerEnter & OnTriggerExit, handle a list of the GameObjects arounds it.
This will have a smoother impact on your CPU instead of a one shot Physics.OverlapSphere.
Don’t forget to clear the list when you reset.
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This works too.
I reccomend bench marking both if performance is critical. Both will behave different in different set ups.
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Thanks. This will be on a lot of object at once so anything to help with performance is welcome.
Will the list of gameobjects keep track of their positions? The objects i want to keep track of will be moving.
Spatial Partitioning (i.e. OctTrees) might be worth some consideration if you are comparing things like hundreds of boids versus a number of attractors and repellants. making a repellant only test distance against boids in a sector (vs all boids in the scene) that encapsulates the repellants range should significantly help with any performance issues.
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Of course, that’s the best way to do that so you end up almost not comparing anything, but i can be much less accurate depending on how much you are partitioning your world isn’t it ?
Unless it’s used as a first filter then you still compare distances under a certain amount of partition around your object.
You can create a list of anything including GameObjects or Transforms:
using System.Collections;
using System.Collections.Generic; // need this to use list
using UnityEngine;
public class Example : MonoBehaviour
{
private List<GameObject> list = new List<GameObject>();
private void OnDisable()
{
list.Clear();
}
void OnTriggerEnter(Collider other)
{
// Filter by using specific layers for this object and "others" instead of using tags
list.Add(other.gameObject);
}
void OnTriggerExit(Collider other)
{
// Filter by using specific layers for this object and "others" instead of using tags
list.Remove(other.gameObject);
}
}
I’ve never heard of OctTrees but i’ll check it out, sounds interesting. Here’s a video that demonstrates what kind of behavior i’d like, and it has a link to the creators websites where you can download a demo of it, if you’re interested.
Well you should use compute shader for that… It will be way more effective to process all of that GPU side.
I know it’s been three years since last comment, but I would like to know, is there any tutorial on how to write such a shader?